Binoculars are popular magnifying objects that help people view things that are too far away to perceive in detail or too scary (birds, animals) to get close to. Since almost any household owns a pair and solar eclipses are fascinatingly beautiful and mysterious, it is obvious that many people will want to use them to watch the sun slip on the moon. However, is it safe to do so, and if not, how can one view an eclipse risk-free?
When looked directly at, the sun can cause serious health problems and in some cases, temporary or permanent blindness might occur. Under no circumstances should one look directly at the star – by directly, we mean without using proper eye protection.
There are specially designed, new astronomy binoculars that can be used to look directly at the sun. We will discuss them later since there is a clever way of observing a solar eclipse with a normal item in a safe manner. In order to do this, you will have to build a projector with binoculars.
The components needed are a normal, everyday product, a tripod or any kind of adjustable support that is solid enough to hold your devices still, duct tape, a sheet of white paper and cardboard.
To assemble the projector, follow the easy steps further described. To begin with, mount the product on the tripod or whatever supporting item you have found and secure them firmly in place with duct tape, making sure that everything is steady and balanced, reducing the risk of falling over.
Draw circles that have the same diameter as the objective and surrounding edges on a piece of cardboard, cut the circles out and tape it in front of the item, with the lenses coming straight through the cutout spaces. Move the binoculars so that they are oriented towards the sun, but DO NOT look at the solar disc.
Stick the sheet of paper to another piece of cardboard so that it is rigid enough to easily handle and place it on the ground, below the eyepieces. After this, turn it and move it around until you can see the sun projected.
As safety precautions, read the manual that accompanied your device to see if they are built to withstand the internal accumulation of heat and do not use the projector for extended periods of time, as it might overheat, on one side, and on the other, the bright spot on the paper might be hot enough to spontaneously ignite. Do not look at the sun and do not leave the ensemble unattended.
In case you want to look at the sun and not at its projection, recent developments in optic technology have allowed solar models to become more affordable and widespread. These are specially designed products that have optic coatings and filters that significantly reduce the solar light’s intensity, allowing for safe observation of the sun.
Non-removable glass filters are usually mounted behind the objective or before the eyepiece lens, but these do not alter the natural colors of the image or the contrasts that may appear. As they only filter white light, the image quality is not reduced; front filters are usually precision polished, to guarantee a maximum quality.
These binoculars cannot be sold as suitable for solar observation without passing serious tests and gaining certification of meeting safety and quality standards. A characteristic of these items is the large field of view and objective, making it easy to locate the solar disk and to observe it.
Keep in mind that only specially designed and certified products are suitable for this task. Do not try to use other products, such as wildlife viewing binoculars or military field glasses to look at the sun as these do not feature protective filters and, even though some might show dimmed images, these will still be bright enough to cause serious problems and even blindness.
It is also not recommended to purchase products sold at general purpose stores, toy stores or hunting/fishing shops. Acquire them from dealers or from authorized online websites only, as these can guarantee that certification has been issued for a particular item. Also, read the instructions with care.
However, if you do not want to invest in a special model, there is another way for observing solar eclipses by using common items. Similar to the projector method, this one only requires a piece of paper and does not need any previous assembly work.
The viewer will post himself with his back towards the solar disk, and hold the binoculars in one hand, aiming it towards the sun by using the shadows on the ground. When it is properly pointed, the shadow will cover a minimal area. Once a position has been found, place the piece of paper under the eyepieces and turn it until you have a good projection.
Albeit the image has a significantly lower quality because your hands will still move no matter how still you try to stay, this method requires no preparatory work and is basically free (provided that you already own a device with a larger field of view and objective).
All these methods are safe and have been proven reliable and efficient by many amateur astronomers around the world who have observed the sun with a minimal budget. Keep your eyes away from direct sunlight and stay safe while enjoying one of the most spectacular naturally occurring events, the solar eclipse.